The present invention is directed to a catalytic reactor for processing an exhaust gases flow from an internal combustion engine, particularly in marine applications, of the type generally employing multiple catalyst elements.
In marine applications, where the engine is enclosed in a compartment, it is common practice to water cool the engine exhaust system to reduce the amount of heat radiated within the enclosure. The addition of a catalytic reactor to such an exhaust system significantly increases the heat within the system so adequate cooling becomes even more important. A problem is that the catalyst element must be maintained at a high enough temperature to sustain catalytic reaction. There is disclosed in U.S. Pat. No. 4,735,046 (Iwai), U.S. Pat. No. 4,848,082 (Takahashi et al.), and German Reference DE 3736500 the use of an insulation gap between the catalyst of a marine engine and a water cooling jacket.
The object of the present invention is to provide an improved thermal barrier between the cooling water and the catalyst element to prevent overcooling the catalyst element and to relieve the thermal shock caused by the extreme temperature difference between the catalyst element, which can be very hot under some engine conditions, and the relatively cold water used as a coolant.